a gunsmith can do it if you feel uncomfortable doing so. it'll take a couple of tools for a 'smith to do a job on it including the stoning or filing of the sear engagement to limit creep. i did mine but left the creep in it. if you want to take some of the creep out of it you'll want to learn the principles involved in re-working the Ruger Model 77 MkII from the diagram and verbage at
www.centerfirecentral.com the adjustments are similar to a Rem' Model 700. with the Rem' you can do it all with 3 screws. with the Vanguard you've got to do some stoning, as i've said, for the trigger creep.
i've done the stoning/filing that is shown on the website above on a few Ruger Model 77 MkII's with great results. i check my sear engagement with grease to see where/how it is wiped off when i trip the trigger. keeping the proper angles on the sear and trigger is very important.
good luck,
ss'